Approximation of the Bivariate Renewal Function

Recently, Kambo and his co-researchers (2012) proposed a method of approximation for evaluating the one-dimensional renewal function based on the first three moments. Their method is simple and elegant, which gives exact values for well-known distributions. In this article, we propose an analogous method for the evaluation of bivariate renewal function based on the first two moments of the variables and their joint moment. The proposed method yields exact results for certain widely used bivariate distributions like bivariate exponential distribution, bivariate Weibull distributions, and bivariate Pareto distributions. An illustrative example in the form of a two-dimensional warranty problem is considered and comparisons of our method are made with the results of other models.     

政府减排目标、产业结构与污染减排

政府是污染减排的重要主体,了解其行为对污染减排的作用对提升污染减排效果及实现中国绿色发展具有重要意义。创造性地将政府减排目标纳入研究框架,构建面板门槛模型,从工业污染排放总量的角度分析政府减排目标、产业结构、经济规模等因素对地方污染减排的影响,并用工业污染物强度进行稳健性检验。结果显示,政府减排目标对污染减排的作用存在阶段性不同:经济发展初级阶段,政府减排目标对污染排放总量的作用方向为正; 经济发展水平较高时,作用方向为负; 两者之间存在适应性调整阶段,作用方向具有不确定性,但总体由正向作用向负向作用转变。产业结构对工业污染排放总量的作用方向因污染物种类而异,经济规模对工业污染排放总量作用方向为正。     

Subjective utility with upper and lower probabilities on finite states

This article is concerned with thresholds of discrimination of preference judgments under uncertainty. We establish an axiomatic characterization for a threshold representation, where thresholds are represented by inexact measurement of subjective probabilities, i.e., upper and lower probabilities. Since upper and lower probabilities need not be additive, the representational form adopts the Choquet integration.     

基于FCM的动态结合全局图像阈值分割

全局阈值分割对于小目标物效果不理想,动态阈值容易产生阴影等干扰,但综合考虑全局阈值和动态阈值可以达到比较理想的结果。模糊C均值算法用于灰度图像分割是一种非监督模糊聚类后再标定的过程,该文在不明显增加运算量的前提下,利用模糊C均值自动聚类的功能分别得到全局阈值和动态阈值,完成对阈值矩阵的构造和图像的分割。     

HEAVY-TAILED-DISTRIBUTED THRESHOLD STOCHASTIC VOLATILITY MODELS IN FINANCIAL TIME SERIES

To capture mean and variance asymmetries and time‐varying volatility in financial time series, we generalize the threshold stochastic volatility (THSV) model and incorporate a heavy‐tailed error distribution. Unlike existing stochastic volatility models, this model simultaneously accounts for uncertainty in the unobserved threshold value and in the time‐delay parameter. Self‐exciting and exogenous threshold variables are considered to investigate the impact of a number of market news variables on volatility changes. Adopting a Bayesian approach, we use Markov chain Monte Carlo methods to estimate all unknown parameters and latent variables. A simulation experiment demonstrates good estimation performance for reasonable sample sizes. In a study of two international financial market indices, we consider two variants of the generalized THSV model, with US market news as the threshold variable. Finally, we compare models using Bayesian forecasting in a value‐at‐risk (VaR) study. The results show that our proposed model can generate more accurate VaR forecasts than can standard models.     

城市规模、创业边界与企业家创业

大城市更有活力且更年轻化的人口结构,导致大城市的消费者异质性偏好更强,进而可能推动企业家创业边界的降低与城市创业活动的发展。为了识别这一理论机制,本文在Zhelobodko et al.（2012）的分析框架上,通过引入城市规模和消费者异质性偏好假设,构建了一个异质性企业家区位选择与创业的空间经济学模型,考察城市规模通过企业家创业边界对城市创业活动的影响,并基于2000-2016年204个城市的面板数据以及2008年中国经济普查数据进行了实证检验。研究发现：（1）企业家才能越高的企业,相应的产品定价会越低,产品需求量越大,而利润越高;（2）企业家创业边界除了受到城市规模的影响以外,还会受到消费者多样性偏好的影响;（3）消费者多样化偏好更强的城市,城市的创业门槛更低,城市的创业活跃度更高。     

环境管制、知识产权保护与区域创新能力——基于我国省际面板数据的实证研究

文章基于政府主导视角,利用2006—2015年我国30个省级面板数据,构建多元回归模型,分析变量之间的关系.其结果显示,环境管制、知识产权保护与区域创新能力之间呈非线性关系,环境管制与知识产权保护同时实施对区域创新能力有显著的促进作用,且具有区域异质性.从企业生存角度出发,提出门槛效应假说,采用Hansen面板门槛回归模型进行检验.结果表明,在环境管制与知识产权保护共同发挥作用时,环境管制必须控制在合理的范围内.最后采用门槛效应回归方法找到了环境管制与知识产权保护对区域创新能力影响的门槛值,并提出相应的政策建议.     

Self-exciting threshold models for time series of counts with a finite range

In this article, an integer-valued self-exciting threshold model with a finite range based on the binomial INARCH(1) model is proposed. Important stochastic properties are derived, and approaches for parameter estimation are discussed. A real-data example about the regional spread of public drunkenness in Pittsburgh demonstrates the applicability of the new model in comparison to existing models. Feasible modifications of the model are presented, which are designed to handle special features such as zero-inflation.     

公共卫生支出、健康结果与卫生投入政策——基于189个国家和地区的面板门槛分析（1995—2011年）

利用189个国家和地区1995—2011年的数据实证检验公共卫生支出规模对一个国家的健康结果（婴儿死亡率和出生时的平均期望寿命）的影响，结果表明，公共卫生支出占GDP的比重对婴儿死亡率和出生时的平均期望寿命的影响具有门槛效应，门槛值分别位于1.9%和6.62%。分段回归结果显示，公共卫生支出占GDP的比重低于1.9%时，公共卫生投入对出生时的平均期望寿命没有显著影响，对婴儿死亡率的影响较弱；超过1.9%后，公共卫生投入的规模效应开始体现，对健康结果指标的影响均显著增强；超过6.62%后，公共卫生投入对婴儿死亡率的影响不再显著，对出生时平均期望寿命的弹性系数不再变化，单位边际贡献不再增加。中国当前政府卫生投入规模仍然较低，需要继续增大公共资金投入、降低个人卫生支出比重。